Exposure meter dial structure



1952 F. P. WILLCOX EXPOSURE METER DIAL STRUCTURE Original Filed Dec 16,1944 vMwww.

Fig.4

1? Vfilleox Frederick Patented Feb. 5, 1952 UNITED STATES iATENT OFFICEEXPOSURE METER DIAL STRUCTURE Frederick P. Willcox, Vestal, N. Y.

Claims.

This invention relates to photoelectric exposure meters, moreparticularly to improvements therein to provide single hand operation,including operation of the calculating dials, and to pro vide directreading of exposure values. By direct reading, I mean the reading ofexposure times and diaphragm openings without the necessity for a mentaltransfer or calculation of a light value reading, as from a meter scaleto a calculator disc.

The present application is a division of my copending application,Serial No. 568,429, filed December 16, 1944, now Patent No. 2,437,774,dated. March 16, 1948. That application discloses and claims a type ofphotoelectric exposure meter in which a variable resistance element isutilized to vary the sensitivity of the meter element, and. to achievean extension of the range of brightnesses for which the meter is directreading, the variable resistance element being controlled by one of thediscs of a calculator dial combination to make the instrument directreading. The advantages of such a construction are fully pointed out inthat application.

The principal object of the invention covered by the present applicationis to provide, for use in combination with a photoelectric exposuremeter, an arrangement of easing, dials and adjusting members which willenable easy and reliable one-hand setting and operation of theinstrument. An ancillary object is to provide such a construction whichwill be physically ru ged and not subject to damage during use, butwhich will at the same time be relatively simple and economical tomanufacture. More specifically, it is an object of my present inventionto provide a structure in which the single dial that is adjusted inaccordance with the light value is especially designed for easymanipulation by the thumb of the hand which holds the meter, and thiswithout subjecting said dial to danger of breakage, such as would be thecase if said dial were merely extended beyond the periphery of the bodyof the meter.

The above and other objects and advantages of my invention will best beunderstood in connection with a single specific embodiment thereofdescribed below, reference being had to the accompanying drawings, ofwhich Figure 1 is a plan view of an exposure meter constructed inaccordance with my invention, Figure 2 is a sectional view thereof takenalong the line .2--2 of Figure 1, Figure 3 is a diagrammatic view ofcertain of the internal parts, and Figure 4 is a wiring diagram of theconnections between the electrical elements.

Referring now to Figure l of the drawings, numeral l designates the caseof the exposure meter, which is provided with narrowed portions 2, 2' onopposite longitudinal sides thereof, and

with rounded rear corners 3, 3'. In the top of the case I, near the rearend, is an arcuate window 4, fitted with a transparent pane 5. Visiblethrough this window is the meter needle 6 and a fiducial mark 1, thearrangement of which will be explained in greater detail below. A ringla for attaching a neck cord or the like, may be secured to case I atits rearward edge.

Mounted upon case i are the calculating discs 8, l2 and I5, discs 8 and12 being arranged for rotational movement about their common center, anddisc l5 being relatively fixed with respect to case I.

It will be seen from Figure 1 that outer disc 8 has a serrated, upturnedperiphery H, which extends just to the edge of case I at a point withineach of the narrowed portions 2, 2'. This construction enables the userto adjust dial or disc 8 by means of the thumb of the hand which holdsthe meter, since the heel of the thumb will lie along the narrowportions 2, 2', with the fingers of the same hand obtaining a firm graspof the meter by virtue of the other of the narrowed portions. Thenarrowed portions 2, 2' hence permit a positive grip of the instrument,regardless of the pressure with which it is held in the hand.

Disc 8 carries two concentric scales, a scale 9 of illumination values(foot-candles), and within that scale, a scale ID of shutter speeds.Scale 9 cooperates with a fiducial mark 911 upon case I. Scale i0,however, cooperates with a scale l3 of diaphragm openings (f-stops)carried by disc i2, which latter disc is relatively fixed in that itretains its position when disc 8 is adjusted, but which can be rotatedby applying force to a struck-up finger l4. Innermost disc I5 is fixedwith respect to case I, but has a cut-out I 6 through which is visible aselected one of a series of film speed indications carried by underlying disc I2.

I have found that it is advantageous to mark scales l0 and [3 upon theirrespective discs 8 and i2 in such a way as to provide a high visibility,for example by using white or bright numbers upon a dull background; Imake scale 9, however, of relatively lower contrast with respect to itsbackground. The purpose of this arrangement is to emphasize the mostcommonly read scales [0 and [3, to avoid confusing the operator with amultiplicity of scales all having the same visibility.

Referring now to Figure 2 of the drawings, and as more particularlydescribed in the application referred to above, one end of case I isclosed by a lenticulated plate ll, behind which, but separatedtherefromby a baffle I9, is the photosensitive element l8. Within thecase is an arcuately shaped resistor 20 whose contact arm 20' rotateswith disc 8 through the intermediary of a bushing 2|. The inner end ofbushing 2| carries a cam 2| which cooperates with a cam follower arm 22(Figure 3) which latter is integrally connected to a fan-shaped mom" rconsisting of two arms 24, 24' carrying portions 25 and 26, the latterof which bears the fiducial mark or member 1 near it shaft 28 passingthrough bushing 2! is mounted with respect to the case i and ser securedisc against rotation.

Within case i is also mounted the usual meter element 25, having amoving pointer Meter 2a is so arranged that the end of pointer 5 travelsin a path just below window 4. rm 22 is pivctally mounted as at 30, andis so nearly coaxial with pointer S that its outer end, and fiducialmember al moi travel nearly parallel over their no A spring 3 i servesto in contact ith cam 25. A backgrou 1 her 32 mount-e within case 1serves to render visible, through-window the pointer and 2.

Meter element '2 may be provided with usual adiusting screw 33,accessible from outside the case removal of a plug 34.

The operation of the exposure meter is very simple. First, the useradjusts disc 52, by me projection it, so that the emulsion speed whichws through window it corresponds to t which he intends to use. He thenaims oe at the object or scene to be ph tog means of the thumb of that eproper exposure (shutter any desired diaphragm opening may from scale13, against the l markings of scale 13 on disc 12. All comhin tions ofdiaphragm opening and shutter sp which will give a correct exposure areobtain d wi .31 the one adjustment.

The instrument may equally well be used. to

In either event, it will be observed that provision of recessed portions2 and 2, and location of main disc 8 with its upturned tions 55 adjacentbut not extending eyond such re essed portions, enable the main disc toadjusted readily by the thumb of whichever hand is used to hold theinstrument. At the same time, the serrated edge 1 l of disc 8, and themechanisms coming within the spirit of my 'ention. Hence, althoughspecific terms have been employed, they are to be understood inillustrative sense, and not for purposes of limita- :ion. I intend toclaim as my invention all such anges and modifications as come withinthe Tn a photoelectric exposure meter, of generally flat, rectangularshape having round d rear corners, and with symmetrically disposed sncavities, said serrations being inclined to the or said case.

2. In an exposure meter, a housing, and a plurality of scale-bearingdiscs mounted upon said housing for relative movement, at least one ofsaid discs having its periphery lying substantially tangent to an edgeof said housing, and a series or" serrations extending upwardly andoutwardly from said periphery at an angle to the plane of said disc.

3. In an exposure meter of the type having a --ousing and a plurality ofscale-bearing discs mounted thereupon with one of said discs having tperiphery lying substantially tangent to an go of said housing, theimprovement which consists of a continuous series of serrationsextending from the periphery of said disc and inclined at an angle tothe plane of said disc, whereby said disc may readily be rotated by thethumb of a user, without loosening the grip upon said housing.

4. For use in combination with an exposure meter of the type having acalculator thereon, a. calculator disc provided with a serratedperipheral portion, the serrations comprising such portion beinginclined at an angle't-c the general plane of said disc.

5. In an exposure meter, a housing comprising opposed parallel majorwall surfaces and edge wall portions extending therebetween, oppositeedge wall portions being dished inwardly through out the depth of saidhousing in regions lying predominately rearwardly of a central axisperpendicular to said major wall surfaces, a calculator disc rotatablymounted on one of said major wall surfaces with its center disposedforwardly of said axis, said disc being dimensioned so that itsperiphery is substantially tangent to the curvatures of said inwardlydished portions,

serrations on the periphery of said disc extending upwardly at an angleto the plane of said disc.

FREDERICK P. WILLCOX.

R-EFEBENGES CITED i'ollowing references are of record in the of thispatent:

OTHER REFERENCES Figures 947 and 948 on page 241 and 940 on page 239 ofMechanical Movements by Gardner D. Wilcox, 7th edition, published byNorman W. Henley and Co. 132 Nassau Street, New York, in 1901.

